Last month, the World Health Organization convened in Geneva, Switzerland and decided that research describing 2 mutant strains of H5N1 avian influenza that are capable of spreading between mammals should be published in full.

The decision to publish data was a controversial one: should the work be published in full to aid pandemic preparedness or redacted to prevent misuse by terrorists? Nature News examines the debate.

The basics:

H5N1 is a subtype of the most virulent of flu viruses to affect humans.

One particular strain of H5N1, called highly pathogenic avian influenza, is responsible for the bird flu scares. It circulates regularly among birds and has jumped to humans on occasion.

Since 2003, the wild virus has infected around 600 people, and 59% died.

Two teams of scientists, led by Ron Fouchier of Erasmus Medical Center in Rotterdam, the Netherlands, and Yoshihiro Kawaoka of the University of Wisconsin-Madison, have created mutant strains of H5N1 avian influenza.

But what makes them dangerous is this: these lab strains are capable of spreading between mammals. The wild virus cannot effectively spread between people… but the mutant strains can spread between ferrets, a good animal model for flu transmission between humans.

Why do this?

The studies provide basic knowledge about the potential of H5N1 to mutate – information that help public health workers monitor wild viruses for similar mutations that make H5N1 more dangerous to humans. That way, health agencies could then advise manufacturers of flu drugs and vaccines to ramp up production, or instigate stricter measures to prevent transmission.

Would that actually work?

It seems unlikely that manufacturers will preemptively produce more vaccine on the basis of a potential threat. And tracking flu mutations is logistically difficult.; surveillance is patchy, especially in poorer countries where H5N1 is most common.

Could the viruses be used in bioterrorism?

Unlike most other bioterror agents, H5N1 can be fought with vaccines and drugs, and cannot be targeted to a specific population. However, a rapid pandemic would overwhelm our ability to manufacture more vaccines and drugs. AND, there are also signs that some wild strains of H5N1 have developed resistance to antiviral drugs.

Could the mutant viruses escape from labs?

Accidental infections of SARS have affected staff at 4 biosafety level-3 (BSL-3) and BSL-4 labs in mainland China. The experiments that created the mutant H5N1 strains were done in BSL-3 'enhanced' labs. The most dangerous viruses, such as Ebola, are studied in BSL-4 labs – with extra safety protocols and more security measures such as bomb-proofing and video surveillance.

Fouchier’s and Kawaoka’s work have been accepted for publication by Science and Nature, respectively.